高边坡节理发育岩体条件下小净距隧道施工的数值模拟

Numerical Simulation for Construction of Small-distance Tunnel Subjected to High Slope in Jointed Rock Mass

以在建石家庄市曹家庄小净距公路隧道为依托,建立离散元UDEC数值力学模型,研究高边坡小净距隧道失稳过程和锚杆支护效果。研究表明在高边坡地形偏压和节理岩体条件下,深埋侧隧道拱肩节理剪切、滑移和张开是整个隧道失稳的主要原因,施工过程中应重点监测。小净距隧道失稳过程为:先从深埋侧隧道拱肩节理剪切滑移开始,然后中夹岩柱发生破坏,最后浅埋侧隧道拱肩失稳,以及整个小净距隧道坍塌。中夹岩柱呈现不均匀变形,最大值在浅埋侧,变形最小值在深埋侧。锚杆能有效控制围岩节理面剪切变形,提高节理抗剪切刚度,从而改善小净距隧道整体稳定性。

By taking of Caojiazhuang small-distance highway tunnel in Shijiazhuang city,UDEC modelling was performed to investigate the instability mode of small-distance tunnel and the enforcement of rock bolts used for small-distance tunnel subject to high slope in jointed rock mass.Inspection of results reveals that failure of spandrel of deeper tunnel is the critical factor associated with the instability of small-distance tunnel.The process of instability is following：failure of spandrel of deeper tunnel take place at first.Then interval pillar ruptures.Sequentially,the small-distance tunnel collapses.Uneven deformation appears at interval pillar.The most deformation takes place at lateral of shallow depth,together with the minimum deformation at deeper lateral.Rock bolts can effectively control the deformation of jointsso as to improve the shear stiffness and stability of small-distance tunnel.